1. Field of the Invention
The present invention relates to a circuit for transmitting electronic signals on a status of an electronic device, and particularly to a circuit for transmitting electronic signals on a status of connectivity between the electronic device and an interface.
2. Description of Related Art
Because of the low transmission speeds of conventional parallel Advanced Technology Attachment (ATA) interfaces, storage devices such as hard drive disks (HDDs) which employ the ATA interfaces are increasingly becoming bottlenecks of computer systems. The introduction of serial ATA interfaces may solve this problem. A serial ATA interface has a higher transmission speed than a parallel ATA interface. For example, the serial ATA1.0 interface has a standard transmission speed of 150 Megabytes per second (Mbps), whereas the parallel ATA/133 interface has a standard transmission speed of only 133 Mbps. And a maximum transmission speed of the serial ATA interface is 600 Mbps. In addition, the serial ATA interface is less complicated than the parallel ATA interface. That is, only four pins or seven pins are needed for meeting the functional requirements of the serial ATA interface. Furthermore, the serial ATA interface has improved extensibility compared to the parallel ATA interface.
When an electronic device employs a serial ATA interface in a particular application, it is necessary to determine whether a bus in the electronic device is being utilized. Conventionally, if the electronic device employs a parallel ATA interface, the electronic device collects relevant data employing a designated pin in the parallel ATA interface. However, in the case of the serial ATA interface, the number of pins of the serial ATA interface is reduced, and there may be no pin available for collecting the relevant data. If an extra signal line is employed to collect the data, this necessarily entails extra costs. Consequently, a circuit is needed for transmitting the needed data without incurring extra costs.